A variety of spectral analyzer models are available on the market currently. Generally, spectral analyzers display frequency domain information for a received signal. Thus, in one example, a spectral analyzer provides a graph that shows frequency on the x-axis and amplitude on the y-axis, thereby giving a user an indication of the relative strengths of various signal components. Generally, the screen is continuously updated as data is generated. An example display of a prior art spectral analyzer is shown in FIG. 1.
Some legacy spectral analyzers provide a user with a split screen display. On the top of the screen is a display of the spectral information in a relatively wide band (i.e., a large scan), and on the bottom is a display of the spectral information for a relatively narrow band within the wide band (i.e., a zoom screen). However, such displays are non-synchronous in that they are limited to having only a single actively updated screen at a time. In other words, legacy analyzers generate data to update one screen or the other at a given time. Thus, a user can toggle between screens, but only one of the screens will appear to the user to be updating at any given time. Further, such analyzers are operable to perform sweep operations in the span of the large screen or in the span of the zoom screen, but not at the same time. Some early legacy spectral analyzers have been limited by a lack of precision in sweeps over wide frequency spans and also a limit to the number of data points collected during a sweep. These two shortcomings force users to evaluate signals by examining spectrum in wide frequency spans, looking for signals of interest, then switching measurement to narrow spans in order to evaluate the characteristics of signals.
Non-synchronous zooms can be acceptable in situations wherein the signal of interest is constant with time. In such examples, a single sweep in a wide span and a single sweep in a narrow span would produce a useful display, since the smaller span screen would faithfully reproduce a zoomed portion of the larger span screen. Most real-world signals, though, are time-varying, such that measurements at two separate times, in effect, measure two different signals.
Some more advanced modern day spectral analyzers have synthesized sweeps over wider arbitrary spans (greater than 10 MHz) and can measure into the thousands of data points. Such data provides visual insight when remotely measured and processed with a computer. For users wanting to make manual measurements with their spectral analyzers, the limit of the display (typically Video Graphics Array (VGA) or Extended Graphics Array (XGA)), offers far fewer pixels than display points measured. FIG. 2 shows a display from a prior art spectral analyzer.
In the example of FIG. 2 a measurement is being taken from 300 to 1000 MHz. The screen attempts to show 8192 total data points that are collected. On this particular instrument the display is VGA (640×480 pixels). Once desktop space and menu space are taken into account, there are approximately 550 pixels available to display the 8192 data points. In this particular example, this translates to about fifteen data points per available pixel (8192/550). In the past, the end user given this issue, would generally choose to narrow the measured span or to split the screen with a wide span at the top and a narrow span at the bottom. However, simply switching to a narrower span display does not allow the user to visualize the full signal. Also, as noted above, prior art, non-synchronous split screens are often inadequate, especially for time-varying signals.